﻿package com.health.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * session ->check_code
 * Servlet implementation class CheckCodeServlet
 */
public class CheckCodeServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	private static Log log = LogFactory.getLog(CheckCodeServlet.class);
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public CheckCodeServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#service(HttpServletRequest request, HttpServletResponse response)
	 */
    private static int width = 65;
    private static int height= 20;
	protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		HttpSession sesison = request.getSession();
		response.setContentType("image/jpeg");
		ServletOutputStream sos = response.getOutputStream();
		
		//设置浏览器不要缓存此图片
		response.setHeader("Pragma", "No_cache");
		response.setHeader("Cache-Control", "no_cache");
		response.setDateHeader("Expires", 0);
		
		//创建内存图像并获得其图形上下文
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		Graphics g = image.getGraphics();
		
		//产生随机的验证码
		char[] rands = generateCheckCode();
		
		//产生图像
		drawBackground(g);
		darwRands(g,rands);
		
		//结束图像的绘制过程
		g.dispose();
		
		//将图像输出到客户端
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		System.out.println(bos);
		ImageIO.write(image, "JPEG", bos);
		byte[] buf = bos.toByteArray();
		response.setContentLength(buf.length);
		
		//下面的语句也可以写成：bos.writeTo(sos);
		sos.write(buf);
		bos.close();
		sos.close();
		
		//将当前验证码存入到Session中
		sesison.setAttribute("check_code", new String(rands));
	}
	
	private void darwRands(Graphics g, char[] rands) {
		g.setColor(Color.BLACK);
		g.setFont(new Font(null,Font.ITALIC|Font.BOLD,18));
		//在不同的高度上输出验证码的每个字符
		g.drawString(" "+rands[0], 1, 17);
		g.drawString(" "+rands[1], 16, 15);
		g.drawString(" "+rands[2], 31, 18);
		g.drawString(" "+rands[3], 46, 16);
		//System.out.println(rands);
	}

	private char[] generateCheckCode() {
		//定义验证码的字符表
		String chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
		char[] rands = new char[4];
		for(int i=0;i<4;i++){
			int rand = (int)(Math.random()*62);
			rands[i] = chars.charAt(rand);
		}
		return rands;
	}
	
	private void drawBackground(Graphics g){
		//画背景
		g.setColor(new Color(0xDCDCDC));
		g.fillRect(0, 0, width, height);
		
		//随机产生120个干扰点
		for (int i = 0; i < 120; i++) {
			int x= (int)(Math.random()*width);
			int y= (int)(Math.random()*height);
			int red= (int)(Math.random()*255);
			int green= (int)(Math.random()*255);
			int blue= (int)(Math.random()*255);
			g.setColor(new Color(red,green,blue));
			g.drawOval(x, y, 1, 0);
		}
	}

}
